The present invention refers to a method for continuously producing a coherent layer of a liquid/melt of even thickness by means of centrifugal action along the entire periphery of a rotating disk, the liquid/melt leaving the disk as individual droplets. The invention also refers to a device for accomplishing the method.
Liquid material can mechanically be finely divided into droplets (particles) in several ways. Recently, centrifugal techniques have been used for the purpose of achieving a smallest possible variation in diameter and of increasing the production capacity when droplets are formed. Originally, these types of device for droplet formation used a perforated wall in a rotating centrifuge in order to generate the actual droplets. A further development of this method has been to let the manufacturing of particles take place from a rotating disk by means of a centrifugal technique. An example of this is the production of spherical particles, where droplets of liquid material by means of centrifugal action are thrown out from the disk and in a subsequent solidifying process are brought to solidify into particles.
In W08807414 a droplet formation method and apparatus is shown, a liquid being distributed onto disks. A distributing means is adapted to distribute the liquid uniformly and circumferentially on the disks. This distributing means comprises a dosing container which is rotationally independent of the disks and from which the liquid is dosed though one or several dosing openings onto the disks. The liquid then spreads radially outwards towards cusps and is divided into particles.
However, the diameter of the particles produced in such a way varies to a different extent, and it has thus been most desirable to be able to produce particles with a smallest possible variation in diameter. In EP-A-0 368 851 attempts have been made to solve this problem by providing the device with a rotating inner distribution means, from which the liquid/melt is supplied to the disk, and the droplets are formed from the outer periphery of the disk by means of centrifugal action. When different types of spraying are used it is likewise important that droplets of uniform size are produced.